复杂槽型车刀片切屑约束与折断预报的研究

在刀片槽型结构对切屑约束的影响研究基础上,建立了复杂槽型车刀片切屑约束与折断预报模型,提出了基于切屑约束的复杂槽型车刀片切屑卷曲与折断预报方法,并进行了三维复杂槽型车刀片切屑约束与折断的试验研究。结果表明:该模型对于复杂槽型车刀片断屑性能的预报和刀片槽型的优选具有实际应用价值。     

硬质合金刀片断屑槽槽型对其切削性能的影响

采用具有多种断屑槽槽型的同种基体材质的刀片进行车削实验,应用高速摄影机捕捉切削区域切屑产生、流出、卷曲和折断过程。通过磨损测量仪观测断屑槽,并结合切屑形态分析,明确断屑槽合理几何形状;通过三维受力分析仪采集切削过程中的振动和切削力信号,揭示断屑槽对切削力的影响规律;综合切削参数、断屑槽几何结构和切削力三方面的因素,最终确立断屑槽槽型与进给量对切屑折断的作用机制。研究数据以期为断屑槽设计与车削刀具的应用提供数据支撑。     

切屑空间运动轨迹及其约束方程的研究

切屑控制技术是现代先进机械制造系统中的基础关键技术，切屑　控制技术不解决，任何一个理想的自动化过程都不能实现。系统研究了切屑的空间运动轨迹　，获得了切屑空间运动轨迹数学模型；建立了切屑在形成过程中与障碍物（工件及刀具）表面　的约束方程。上述研究成果是研究切屑形成与折断过程的有效途径，为进行刀片槽型优选及　设计以及切屑折断预报系统的研制奠定理论基础。     

复杂槽型数控车刀片断屑预报系统的研究

针对数控车削加工过程中切屑折断难以预测问题,依据切屑折断界限理论建立了极限进给量和极限切削深度的预报数学模型:以上述数学模型为核心,开发了复杂槽型数控车刀片的断屑预报系统.为了验证预报结果的准确性,选取了典型的复杂断屑槽型车刀片切削45钢的断屑试验结果与预报结果进行了对比,对比结果显示二者基本一致,从而证明断屑预报结果的准确性和断屑预报系统具有一定的实用性.     

基于MATLAB的车刀片三维复杂槽型设计

提出了一种三维复杂槽型车刀片的槽型设计方法;将有效槽型参数运用于切屑折断卷曲半径和切屑折断条件式,导出三维复杂槽型的槽宽的计算式;并用MATLAB计算出槽宽,拟合出槽型的曲线;计算出的槽宽可导入Pro/Engineer建立三维复杂槽型车刀片的模型,该模型可以导入ANSYS软件进行槽型车刀片的切削仿真,分析槽型的性能,为以后槽型设计的系列化,参数化,打下了基础.     

硬质合金刀片嵌入式辅助断屑器的设计

为了扩大硬质合金刀片的断屑范围,结合硬质合金刀片三维槽型的结构特征和刀片安装方式,设计并制作了一种嵌入式辅助断屑器。进行了铝合金切削实验,观察了切屑形貌,并分析了切屑折断机理。实验结果表明,未安装嵌入式辅助断屑器时,硬质合金刀片在小切深下可以实现断屑;但在大切深时,产生长螺卷屑,硬质合金刀片的断屑效果变差。安装嵌入式辅助断屑器后,在大切深时,硬质合金刀片产生了C形屑。嵌入式辅助断屑器的反屑面增加了断屑台的高度和角度,进一步减小了切屑的卷曲半径,促进了切屑的折断。安装了嵌入式辅助断屑器的刀片具有较高的断屑率,扩大了硬质合金刀片的断屑范围。     

切屑折断界限的理论研究

从上向弯曲切屑折断界限理论出发,推导出刀片二维槽形切屑流出圆半径及极限进给量的理论预报公式;根据横向卷曲短螺卷屑形成过程中切屑动力学及其折断判据理论,得出了极限背吃刀量的理论预报公式;并通过系统的试验研究,证明试验结果与理论预报结果比较符合。为刀片三维槽形的槽形设计及断屑预报系统建立打下理论基础。     

基于UG二次开发的可转位刀片断屑槽参数化设计

断屑槽设计至关重要,切屑折断主要取决于断屑槽的形状和几何参数。本文通过试验手段分析车削不锈钢材料时不同切削参数下的切屑形态,研究不同切削参数下切屑折断的难易程度。由于断屑槽形状具有不规则性,采用常规的设计方法进行设计工作量大,重复性高,效率低下。针对该问题,提出了一种基于UG二次开发的断屑槽参数化设计方法。以UG作为平台,应用其强大的二次开发工具UG/Open API,以断屑槽设计方法和尺寸标准为依据,开发运行于UG上的人机交互的断屑槽参数化系统。该系统降低了设计人员的劳动强度,缩短了槽型设计的开发周期和车削加工周期。     

减摩槽刀片切削过程的Deform仿真

在刀片上设计减摩槽,理论上可以减小刀屑接触面积,进而减小切削力。目前,对减摩槽刀片的研究仍停留在切削实验阶段。本文用Deform 3D软件对有无减摩槽的两种刀片进行了模拟仿真,分析了减摩槽对切削力大小、切削温度、切屑的有效应力及刀具塑性变形的影响。仿真结果对刀具减摩槽的设计及选用具有参考价值。     

断屑槽型的计算机辅助设计

本文是根据切屑折断界限理论，进行的二维断屑槽型可转位刀片计算机辅助设计的总结，使用本文所述ＣＡＤ系统，可实现ＴＮＭＭ，ＳＮＭＭ三种ＣＮＭＭ（３５°，５５°，８０°）刀片５种尺寸规格的自动设计。     

深孔钻削切屑形态的研究

通过试验研究了φ14 mm的YT15刀片BTA钻、涂层刀片BTA钻和陶瓷刀片BTA钻在不同切削参数的切屑形态和切屑容屑系数λ(λ为单位体积金属的切屑所具有的容积)对排屑的影响,试验表明,切屑容屑系数越小排屑越好,而且C形切屑的切屑容屑系数最小,对排屑最有利。     

Efficient Chip Breaker Design by Predicting the Chip Breaking Performance

As machining technology develops toward the unmanned and automated system, the need for chip control is considered increasingly important, especially in continuous machining such as in the turning operation. In this study, a systematic chip breaking prediction method is proposed using a 3D cutting model with the equivalent parameter concept. To verify the model, four inserts with different chip breaker parameters were tested and their chip breaking areas were compared with those obtained from the model. Finally, a new type insert (MF1) for medium-finish operations with variable parameters was designed by modifying the commercial one. The chip breaking region predicted by using the modified 3D cutting model for the above insert agrees with the one obtained experimentally. The newly designed insert showed better chip breaking ability than the base model, and other performance tests such as surface roughness, cutting force and tool wear also showed good results.     

A knowledge-based approach for designing effective grooved chip breakers — 2D and 3D chip flow,chip curl and chip breaking

This paper presents details of a knowledge-based approach for designing effective grooved chip breakers for two- and three-dimensional chip flow, curl and breaking. The design criterion used in formulating this new approach is effective chip breaking at minimum power consumption. This work was aimed at achieving the optimum groove parameters and the best utilisation of groove profile under varying machining conditions. A systematic knowledge-pool was established from a series of well-designed machining experiments which form four knowledge databases (reference database, grooved chip breaker database, natural contact length database and 3D chip flow database). This paper shows how the chip breaker design parameters can be estimated for effective chip breaking at reduced power consumption. The basic tool design strategy presented in the paper also includes some guidelines, for cutting tool designers, highlighting the need for implementing a scientific approach for designing a chip breaker against the current practice of try and see methods.     

Development of web-based machining chip breaking prediction systems

The prediction of chip breaking in machining is an important task of automated manufacturing. A chip breaking predictive model has been developed to predict the chip breaking behaviour in steel turning with grooved tools. The model is based on the chip breaking limits theory. A web-based chip breaking prediction system has been developed and presented in this paper with industrial application examples. With the system, the chip breaking range in steel turning with grooved tools can be predicted under different cutting conditions. The experimental data for turning different steel material over a wide range of feed rates, cutting speeds and tool geometry showed agreements with the model prediction. The user-friendly system is accessible through the Internet for the purposes of cutting condition design and tool selection. Also, the system can easily be extended to contain new cutting tools and new workpiece materials with a small number of cutting tests.Nomenclature f Feed rate (mm/rev) - d Depth of cut (mm) - V Cutting speed (m/min) - f_cr The critical feed rate (mm/rev) - d_cr The critical depth of cut (mm) - r Insert Nose radius (mm) - W_n Insert chip breaking groove width (mm) - Cutting edge angle (deg) - ₀ Insert rake angle (deg) - ₀₁ Insert land rake angle (deg) - b₁ Insert/chip restricted contact length (mm) - _s Insert inclination angle (deg) - h Insert backwall height (mm) - WP Work piece - DB database     

IMPULSIVE CHIP BREAKING IN METAL MACHINING: A PROOF-OF-CONCEPT STUDY

An innovative non-conventional technique, called impulsive chip breaking, is developed in the present study to break difficult-to-break chips that are often generated in machining high toughness or soft gummy materials, such as pure aluminum, pure copper, aluminum alloys, copper alloys, low carbon steels, and stainless steels. These materials have a wide variety of engineering applications. In impulsive chip breaking, the machine tool spindle rotational speed periodically increases to a prescribed higher speed within a set short period of time and then resumes to its normal constant speed to continue machining operations. The experimental investigations covering a range of cutting conditions on a selected work material are preformed to confirm the feasibility of impulsive chip breaking and study its basic mechanism as well as the characteristic variations of machining performances, including the chip morphology, the cutting forces, the machining vibrations, and the surface roughness of the machined workpiece. It is demonstrated that as long as the impulsive rotational speed of the machine tool spindle is appropriately selected or optimized, both requirements of breaking chips and maintaining the machined surface quality can be simultaneously satisfied.     

内冷式高压冷却车刀切削性能的研究

研究中对关于切削温度和切屑折断方面新型内冷式高压冷却车刀的切削性能进行了仿真和实验分析。研究结果表明,在切削过程中喷射的高压冷却液可以最大限度地带走刀-屑-工件系统中的热量,使冷却更高效,还可以通过改变润滑摩擦条件和剪切角度(剪切性能)来改善切削状况,迫使切屑卷曲折断并强烈控制切屑的形成。最终在高压射流的热效应和机械效应的综合作用下,改善切削温度的同时得到较小弯曲半径的碎屑,从而增强了切削过程中的工艺稳定性和加工安全性。     

IMPULSIVE CHIP BREAKING IN METAL MACHINING: A PROOF-OF-CONCEPT STUDY

An innovative non-conventional technique, called impulsive chip breaking, is developed in the present study to break difficult-to-break chips that are often generated in machining high toughness or soft gummy materials, such as pure aluminum, pure copper, aluminum alloys, copper alloys, low carbon steels, and stainless steels. These materials have a wide variety of engineering applications. In impulsive chip breaking, the machine tool spindle rotational speed periodically increases to a prescribed higher speed within a set short period of time and then resumes to its normal constant speed to continue machining operations. The experimental investigations covering a range of cutting conditions on a selected work material are preformed to confirm the feasibility of impulsive chip breaking and study its basic mechanism as well as the characteristic variations of machining performances, including the chip morphology, the cutting forces, the machining vibrations, and the surface roughness of the machined workpiece. It is demonstrated that as long as the impulsive rotational speed of the machine tool spindle is appropriately selected or optimized, both requirements of breaking chips and maintaining the machined surface quality can be simultaneously satisfied.     

基于人工神经网络的车削切屑形态预测动态建模及实时仿真

针对数控加工中切屑形成过程的监控问题,在基于实时工况智能监控平台上,通过研究切屑形态预测的神经网络动态建模方法,建立了切屑形态预测仿真动态模型.并根据切屑空间运动轨迹的数学模型,建立了切屑三维造型模型,在虚拟现实环境中实现车削过程的切屑实时动态仿真.     

切屑折断过程的基础研究及虚拟现实

在VisualC ++6 0环境下 ,结合OpenGL和WorldToolKit软件构建桌面虚拟现实的软件平台 ,并对相关的切屑空间运动轨迹和切屑折断数学模型进行推导整理 ,将其挂接到虚拟现实编程环境下 ,实现切屑折断过程的仿真 ;最后通过立体眼镜等组成的硬件平台 ,实现在一定加工条件下输入不同刀具几何参数与工艺参数 ,完成切屑折断过程的虚拟现实     

AZ91D镁合金加工工艺的应用研究

在分析AZ91D镁合金化学成分、物理力学性能的基础上,通过试验对比了切削速度在66.819m/min、107.388m/min、169.434m/min时的切屑断屑性能、切屑形态及其表面质量。试验表明:在背吃刀量恒定的前提下,随着切削速度的提高,切屑变形减小。切屑形态由C形挤裂切屑变成带状连续切屑,断屑能力变差,结构表面质量变差;在背吃刀量0.06mm时,切削形成粉末状切屑,堆积在卷屑槽内,易引起镁合金燃烧。总结了镁合金切削加工中对刀具、切削参数、切削液以及切削过程的要求,介绍了工序间防腐措施。分析了AZ91D镁合金的固溶时效作用,从零件结构、设备及防火等方面提出了热处理过程的要求。从冶金和环境方面综述了镁合金的腐蚀因素,并对比分析了AZ91D镁合金切屑在空气和水中的腐蚀现象。最后,重点介绍了镁合金的微弧氧化工艺。研究成果对镁合金加工工艺的推广应用提供了技术参考。